JACK: Pretty specific directions. Most people tell me to be somewhere, they say west on the 40, this or that exit. Second gas station on the left, you know?

Jack raises his hand which has coordinates written on it

In the last episode, “To'hajiilee”, Jesse outsmarted Walt and in a panic Walt called Jack for support. In the panic he gave Jack exact co-ordinates to where he is, not realizing how suspicious that’d be

This is the moment where we as the audience realize that Jack is smarter than he seems. Part of the reason he really came to “rescue” Walt was because he knew there had to be something about that coordinate Walt gave him